Telephone system



March 8, 1938. A. SZILARD ET AL 5 Sheets-Sheet 1 TELEPHONE SYSTEM Filed May 17, 1935 fnveniars:

x r mi W/tnesses March 8, 1938. sz ET AL 2,110,312

TELEPHONE SYSTEM I Filed May 17, 1935 3 Sheets-Sheet 2 H F Va 1 a 1 i i 2 4 1 3 K1. H F, n b M I Witnasses:

March 8, 1938. A. SZILARD ET AL 2,110,312

TELEPHONE SYSTEM Filed May 17, 1935 s Sheets-Sheet s Patented Mar. 8, 1938 TELEPHONE SYSTEM Adalbert Szilard and Georg Keleti, Budapest, Hungary Application May 17, 1935, Serial No. 22,09!

In Austria May 23, 1934 8 Claims.

The invention relates to an arrangement for telephone systems suitable for automatic connection of calling subscribers A with a central message oilice in case the called subscriber B is not available to answer the call, permitting the interchange of messages in both directions by means ofsimple auxiliary devices disposedat the subscribers B and of a combined switching and indicating device, common for a group of such subscribers B.

Arrangements for similar purposes are in use, but these known arrangements do not allow the subscribers B to send messages to the calling subscribers A without a previous call of B to the message ofllce. In these known arrangements the recording of these messages in the message ofllce requires a great amount of operator's work, furthermore they have the drawback of comparatively high first cost for each subscriber and in s some cases of considerable power consumption even during the time of no conversation.

On the other hand, the arrangement according to the present invention is such that frequently wanted, stereotype messages of the subscriber B which he desires to be transmitted to all subscribers A calling him, are neither to be communicated beforehand to the message ofllce, nor to be recorded there and to be selected from these records in case of a call of a subscriber A. The stereotype message set up by B is automatically indicated to the operator of the message oflice simultaneously with the call of subscriber A or the message is transmitted by means of suitable reproducing apparatus in a fully automatic manner.

In the figures of the annexed drawings Fig. 1 shows diagrammatically, the arrangement in principle of an apparatus according to the invention,

Figs. 2 and 3 each illustrate an embodiment, shown by way of example, of an apparatus according to the invention,

Fig. 4 shows the detail of a further arrangement, in principle, and

Figs. 5 and 6 illustrate details appertaining to the embodiment shown in Fig. 2 and in Figs. 2 and 3, respectively.

The idea of the invention is best explained by reference to the diagram shown on Fig. 1. An auxiliary device I is provided at subscribers B, this device being operated by B, if he desires that subscribers A, calling him thereafter, shall be connected to the message ofllce. There is also a central combined switching and indicating device 2, common for a group of subscribers B. By operating the auxiliary device I, peculiar predetermined current and voltage conditions may be produced in line 3 of subscriber B, and thereby, according to the invention, device 2 is influenced in such a manner that a calling subscriber A is connected automatically to the message oflice and the interchange of messages is made possible either over the operator's set N or by means of automatic speech or signal recording and reproducing apparatus Z. According to the invention, for each message chosen by B from a plurality of stereotype messages to be transmitted to calling subscribers A, there is a corresponding predetermined different manner of operation of device I, causing corresponding peculiar current and voltage conditions in line 3 and a corresponding manner of influencing device 2. The manner in which device 2 has been influenced is observed by the operator at N who transmits the corresponding stereotype message to the subscriber A or this message is communicated automatically, according to the manner in which device 2 has been influenced, by means of apparatus Z in form of signals or speech reproduction. Transmission of messages which are not stereotype addressed by B to A and recorded beforehand, and the recording of messages addressed by A to B, are effected either by operators or by automatic recording and reproducing apparatus Z. As shown hereinafter, for communications between B and the message office a direct connection over device 2 and line 3 may be used without any cooperation of the normal switching apparatus of the exchange.

An embodiment of the invention is shown in Fig. 2. A is the calling subscriber, B the called subscriber, VA the automatic telephone exchange, to which B is connected, I the auxiliary device at B, 2 the common switching and indicating device for all subscribers of the same exchange VA.,and a and b the two wires of line 3 of subscriber B. The auxiliary device I comprises in this case the switch 8 and a variable alternating current resistance, composed of a variable condenser K and a variable induction coil W; for each stereotype message of B a fixed value of the A. C. resistance is allotted with fixed values of K and W. The wires (1 and b of subscribers B are connected to corresponding contacts of two contact banks of finder Sr, having three wipers. The primary windings of transformers T are arranged in wires b, whilst one end of the secondary windings is grounded and the other end is wired to the third contact bank of finder S1. The finder is permanently driven by the stepping magnet M1, as long as there is no incoming call for a non-answering subscriber B. When a call is made, to a subscriber'B who has operated his switch 8, thereby disconnecting his subscriber's set'and connecting up his auxiliary device I, a

ringing current of less intensity will result, the

resistance oi device I at the frequency of the ringing current being greater than that of the subscrlber's set. As soonas the finder sr reaches" the contacts oi B. the ringing voltage lstransmitted by wipers'Sa audit) to the amplifier V1 and in its output circuit relay R1 will operate. At

the same time amplifier Va is also influenced by transiormer T and wiper St, but relay. Rs in the output circuit oi amplifier V: does not. operate, this latter being adjusted to operate only it the normal ringing current is flowing in wire b. .In this way relay R: is energized by hand a, operatesand opens at rm the circuit 01' magnet M1,

and in consequenoethereoi finder Sr stops. R:

locks up through Tu, and wires and b are'extended by r. and'rs. after having been momentarily short-circuitedduring switching at the precontacts 1'" and-n"; so u to bring the apparatus in the 'exchange'iVA into the'talking position.

Finally the circuit oiusteppingma'gnet Ma oi se-j lector We. is closed atrm. Selector Wa rotates anew its wiper Wt successively connects diiierent oscillatingcircuit 81s to the grid of oscillator tube Sefeach frequency of the oscillator tube corresponds to a ireouency tuned up by. a" certain settingoi device 'I. 'As soon as the sameireql'sency messag'esi and these machines are connected to the contacts oi the arc oi movement of the wiper We in the'proper sequence, so thatthe caller has transmitted tom the message which corresponds" to the manner in which theauxiliary device has been operated. The talking thus transmits to subscriber A any message set ondevice I, the operator communicates the special non-stereotype mesjsage are andrecords themessage oi A addressed t'oBL the operator presses'the key Tr,

thereby device I and the operation may thereuponbe repeated as described.

bodiment is shown in Fig.3, The

auxiliary device iconsists oi anal-V ternating currentdropF,connectedacrosswires sand I; in series with a condenser K, and oi a buzsensu in series with a stepping magnet it connected alsoacross the wires sand b as soon as the drop F ialis. 'lhe stereotype message is set up by ad u t n stop A r sasinse s-y a camdisc, thereby allowing a ratchet wheel Kl driven by magnet M and keyedon a common shaitwith the cam disc. to rotatea certain'num- 'ber oi steps corresponding to the serial number oi the message. Device 1. comprises a finder Sr ew'ith two wipers. The wires 4 and b oi sub- I scribers 'B are connected to the contact banks, oi

Sr. Wipers Ba and 8b are connected by back contacts of R1 to thefinput terminals oi a'gbandpass amplifier V tuned to the irequency oi buzzer Thewindingoirelelfliisconnectedtothe oi V. when B been closedandB is called.drop1" iallatmder action oi the ringing current "Inthe cascoibotharrangements -mitted to the common relays.

cannot follow the quick vibrations of the bullet,

in consequence whereoi it remains attracted during the time the buzzer is working. As soon as, the finder Sr reaches the line of B, relay R1 is energized by V, operates and opens at the cir- 5 cult of the stepping magnet M1 or finder 8 and as aresult Sr stops. R1 locks. up through Ta and m and extends the wires a and below '1 and n- This done, relay R2 operatesby r: and the mew subscriber B, the wire a being earthed in VA. Rs 10 closes at r: the circuit 6! st magnet of anin'dicator dial Scmm operates, Sch makes a step; and M3 grounds wire b'by contact I, in

consequence whereoi magnet M of device I is, released and the ratchet wheel K1 makes a step accordingly. Magnet M: comprises a self-interrupter; not shown .in the. figure, which opens the energizing circuit as soonasthe armature has] been attracted, therefore M; ialls back aiter each attraction. This play oi Ma and M is repeated. until the rotation of ratchet wheel K1 is limited by the stop An. Then the ratchet wheel K1 re turns to its normal position under action oi a spring, not shown on the figure, tensioned during the stepping of K1 and released by An; drop lie at the same time restored Thus the loop of subscriber B','i. eithe circuit oi Rs, is'opened. and in consequencem cannot be energlzed again. Dlal sch stops aitera's many steps as the. ratchet wheel K1 waslallowed to :periorm bythe adjustablestop An. 1 Contact K: which is open only in the normal position oi dial Bob, is nowclosed and relay Rois energizedby the back contact 1'2, disconnecting; R: from wire b at 's and extending wiresa and b along rs. and Ta to the operator's set N. Now the operator can read the stereotype message indicated bythe: position 0! dial Sch and recognizes from the position oi find! er Sr, which subscriber has been called. After the communication and reception of the messagq the operatorpresses key.'1r,thereby mechanically releasing dial Sch. which returns to normal position under action oi a spring Relay 86 I energized by-the iront contact. oi and locks up through contacts rlsand Tu; Assets:

, as dial Sch has reachedits normal position, on

circuit of relay R: is ,opened at contact Ks, then .R: releases, the operatorsset is disconnected, and

the-locking clrcuitoiR-eisopened at oi R1 is opened at run'lhe circuit oi H1 is closed so again-Vat rm. Finder Br moves on and the whole operation .is repeated as soon as itreaches the 'line oi another subscriber who may be called and 'who does not answer.

employment or individual relays ior each subscriber for the device 2' has been" avoided. this beingrendered possible bythe employment at the amplifiers described. by means oi which the signals arriving from the-various lines are trans- I Arrangements are, however, also possible, which do not require any amplifier butrequire the employment (I individual relays ior each subscriber;

- The action oi the 'auxiliarydevice I by which it connects A with device land the signal'transmission between devices I and I i. e. the kind e! peculiar current and voltage conditions, caused by device'i in linel, may be difierentirom those --oi the embodiments described above. Boreaample, device 2 may be influenced by varying the intensity, 'irequency, phase, or somelother characteristics oithe ringingtl' food; current, or by supplying'currents or ioreignsourcesprovidcdatBorelsewhereIhiohfl iii are influenced by device I and affect device 2 over line 3 accordingly.

According to the invention the operation of the switching and indicating device 2 may be made automatic in a greater measure than described as above e. g. by using for recording oi the messages of A addressed to B speech recording apparatus acting in a well known manner.

In the message omce provision is to be made for one or, depending on trafllc requirements, more oflice lines for communication with subscribers. According to the invention a direct connection over lines 3 and device 2 may be used for the communication between subscribers B and the message oflice, without the cooperation oi. the switching apparatus of exchange VA whereby a certain manner of operation oi! auxiliary device i may set up a direct connection with the operators set N over line 3 and device 2. For example, in the embodiment of Fig. 3 this may be effected by directing the buzzer's tone from the auxiliary device I over the resistance W1 and switch S1 in Fig. 5 to the line 3, thereby causing device 2 to stop on the respective line I and to establish the connection to N in the manner described above.

According to the invention an additional device may be provided at B which indicates if B has been called during the non-answering period, in order to induce B to inquire at the message oflice: Furthermore the calls may be registered at B or in the message oflice by means of metering devices e. g. for accounting purposes, or the time of engagement of device 2, of the operator, or of apparatus Z may be recorded continuously and separately for each subscriber.

During the time when device I is in the nonanswering condition, the bell may be left connected, possibly with a weaker tone, in order to make B cognizant of the call, should he have forgotten to restore his device I into the answering condition. By these means the operator is enabled to give a special ringing signal to subscriber B in urgent cases and in those which have been previously pointed out by B or marked as desirable by setting his device I accordingly.

According to the invention it the trafiic with the message office is very intensive, further switching and indicating devices 2' shown in Fig. 1 may be employed for the same group of subscribers, in which case provision should be made in ways for avoiding double connections.

On the other hand, certain parts of the switching and indicating device may also be common for various groups of subscribers, as shown in Fig. 4. In other cases, when the traflic is moderate, as at night, etc. the service-oi! several devices 2 serving difierent groups of subscribers (e. g. in different exchanges VA) may be combined; in this case some parts of device 2 will be situated at a considerable distance from the others and connected with them over trunk lines. In such cases such indications oi. device 2 which cannot be read directly, are to be transmitted to the operator over trunk lines-in known manner.

In order to accelerate operation, according to the invention, lamp indicators working in well known manner may be used for the indication of the positions.

A certain part of the stereotype messages will be the same for all subscribers B, e. g. the cause of failure to answer: absence, nighttime etc.; furthermore certain limitations of answering, e. g.

only for toll calls; finally the time of the next reply condition and the like. According to the invention, provision can be made for a number scriber B, e. g. communication of the directory numbers, at which he may be reached at the time being. In this case the selection 01 the meaning of various readings of device 2 for each subscriber B from records by the operator may be avoided by the use of a combined indicating apparatus for this kind of messages-stereotype for anyone subscriber B, but diiferent for different subscribers B--the indications thereof being dependent not only on the particular subscriber B who was called, but also on the setting of the called subscribers device I. Such a combined indicating apparatus is shown in Fig. 6. Wiper S11 is fixed on the shaft of the finder Sr whilst wiper S1: is fixed on the shaft of the disc Sch as in Fig. 3, so that wiper 811 will switch the indicator lamp of the called subscriber, whilst wiper SI: will switch the indicator lamp corresponding to the serial number of the message. Thus the message *to be transmitted may be read at the crossingpoint oi the row and column marked by lit up lamps.

Having now fully described and ascertained our said inventionand the manner in which it is to be performed, we declare that what we claim is:

1. A telephone system for the interchange of messages between calling and non-answering called subscribers, comprising a message oflice, an auxiliary device atthe called station operable to produce predetermined difierent current or voltage conditions in the called line, means for setting said auxiliary device to operate in a selected manner, a signal operable in predetermined difierent ways corresponding to the diiierentsettings of said auxiliary device, switching and indicating apparatus common for a group 0! called subscribers and responsive to said different current or voltage conditions, and means controlled by said apparatus ior connecting the calling subscriber to the message office and for actuating said signal in accordance with the setting of said auxiliary device.

2. A telephone system for the interchange of messages between calling and non-answering called subscribers, comprising a message ofllce, an auxiliary device at the called station operable to produce predetermined difierent current or voltage conditions in the called line, means for setting said auxiliary device to operate in a selected manner, a signal operable in predetermined different ways corresponding to the different settings of said auxiliary device, switching and indicating apparatus common for a group of called subscribers and includingflnders responsive to the difierent current or voltage conditions in a particular called subscribers line, and means controlled by said apparatus for connecting the calling subscriber to the message omce and for actuating said signal in accordance with the setting oi said auxiliary device.

3. A telephone system as set forth in claim 2, said finders comprising parts adapted to move in a step-by-step manner.

4. A telephone system for the interchange of messages between calling and non-answering called subscribers, comprising a message oince, an auxiliary device at the called station operable to produce predetermined diii'erent current or voltage conditions in the called line, means for setting said auxiliary device to operate in a selected manner, a signal operable in predetermined different ways corresponding to the different settings of said auxiliary device, switching and indicating apparatus common for a group of called subscribers and responsive dlilerent rent or voltage conditions, and means controlled by said apparatm i'or connectingthe calling subscriber to the message once and for actuating ma signal in accordance with the setting .0! said auxiliary device; ma switchingapparatus comprising an amplifier responsive to said diiierent ,current or voltageconditions, and underminfluenced by said amplifier, said finders comprising parts adapted to move in a step-by-step manner.

; 5. Aatelephone m the interchange oi I messages between calling and non-answering called subscribers, comprising a messageoflice,

.;an auxiliary device at the called station operable to produce predetermined diilerent currentor voltage conditions in the called line, ior

setting said auxiliary devicegtooperate in a selected manner, a signal operable in predetermined d'lil'erent ways corresponding to thediflferent set.-

wtings oi said au dliarydevice. switching and indicating'apparatus common for a group of calledr subscribers and responsive to said diii'enent current or voltage conditions, and means controlled by said' apparatus for connecting the calling subscriber to the message omce and Ioractuating "said signal in accordance with thesetting of said auxiliary device; said switching apparatus comprising a means responsive to said diiierent current or voltage conditions, and finders influenced by saidmeans, said finders comprising parts adapted to move in a stepqby-step manner.

' 6. In a telephone system, .the combination with Y the elements set forth in claim-1' oi an indicating device associated with said switching apparatus,

and means for automatically causing said indicating device to function so as to indicate which particular subscriber has been called.

a,11'o,s1a w curi fl; In a telephone system, an unattendedsubscflbersstation, a subscriber's set, a messagestoring. and -se'nding device having a'plurality voi? possible settings corresponding to ,diilerent predetermined stereotype messages and connectabie to subscriber's linean operator's position, an operator's set,an,indicating device at said operator's comma switch having accessto saidwubscriber's line and responsive to incoming to, said subscribers line for completing T .aftalking connection between the calling subscriber and-the operator'at said position and simultaneously establishing a signal transmission over said subscriber's line between said message-storing and -sending device and said indicating device.

ii. In a telephone system, an unattended so a i and -'sending device and said message-indicating device both comprising parts movable in a stepby-step manner and adapted to operate Iin'synchronism it connected one-to the other over said subscriber's line.

GEQRG ADALBERT i Y 

